topic one- biological molecules Flashcards
what are polymers
large, complex molecules composed of long chains of monomers joined together
what are monomers
small, basic molecular units that can form a polymer
eg- monosaccharides, amino acids and nucleotides
how are polymers formed
through a condensation reaction with the monomers
a condensation reaction forms a chemical bond between monomers, releasing a water molecule
think the h20 is removed from the end of each monomers bond so then they form bonds with each other
how are polymers broken down into monomers
through a hydrolysis reaction
a hydrolysis reaction breaks the chemical bond between monomers using a water molecule
think that the h20 has been added back so it breaks the bond and gives each monomer end the correct OH ending so they cannot bond to each other anymore
what is meant generally by the term sugars
monosaccharides and disaccharides
what is a saccharide
a sugar
what elements do all carbohydrates contain
C,H,O
what is glucose and how many types are there
it is a monosaccharide and there are two types:
alpha glucose (OH connected to the carbon1 is bellow)
Beta glucose (OH connected to the carbon1 is above)
remember A.B.B.A
how many carbon atoms does glucose have
6 as it is a hexose sugar
what is a disaccharide and how is it formed
it is formed when two monosaccharides join together.
monosaccharides are are joined together by condensation reactions
a glycosidic bond is formed between the two monosaccharides as a molecule of water is released
what does hydrolysis mean
break something up using water
remember olysis means to break up eg- electrolysis
what is sucrose and how is it formed
it is a disaccharide formed from a condensation reaction between GLUCOSE molecule and a FRUCTOSE
how is LACTOSE made
it is a disaccharide formed formed formed from a condensation reaction with a GLUCOSE molecule and GALACTOSE molecule
how is MALTOSE made
it is a disaccharide formed from condensation of two GLUCOSE molecules
what are the three disaccharides you should know and what they are made from
MALTOSE- condensation of 2 GLUCOSE molecules
LACTOSE- condensation of GLUCOSE molecule and GALACTOSE molecule
SUCROSE- condensation of a GLUCOSE molecule and a fructose molecule
what bonds hold together the joining molecules in saccharides
glycosidic bonds
what do these prefix mean
mono
di
poly
one
two
many
what is a polysaccharide and how is it formed
it is formed when two or more monosaccharides are joined together (by glycocydic bonds) in a condensation reaction
polysaccharides can also be broken down into their monosaccharides by a hydrolysis reaction
what are the monosaccharides you need to know
glucose, galactose , fructose
what are the disaccharides you need to know
maltose, lactose, sucrose
what are the polysaccharides you need to know
starch, glycogen and cellulose
what is the formula for glucose
C6 H12 06
STARCH storage
cells get energy from glucose, and PLANTS store excess glucose as STARCH
when a plant needs more energy it breaks down the starch back into glucose
what is STARCH made from
starch is a mixture of two polysaccharides of AMYLOSE and AMYLOPECTIN
what is STARCH function
-cells get energy from glucose, plants store excess glucose as starch (so when a plant needs more glucose for energy, it breaks down starch back into glucose)
- mixture of two POLYSACCHARIDES of ALPHA-GLUCOSE
AMYLOSE AND AMYLOPECTIN
AMYLOSE- long ,UNBRANCHED chain of a-glucose, the ANGLES of the GLYCOSISIDC bonds give it a COILED STRUCTURE- this makes it COMPACT so makes it REALLY GOOD FOR STORAGE, as FIT MORE INTO SMALL SPACE.
AMYLOPECTIN- long, BRANCHED chain of a-glucose- BRANCHES allow the GLYCOCIDIC BONDS to be broken down quicker (as enzyme can get to them easier) this means that the GLUCOSE can be released quickly.
STARCH IS INSOLUBLE as is so large so doesn’t affect the WATER POTENTIAL of the cell so doesn’t affect OSMOSIS
what is starch made out of which allows it to be a good storage molecule in plants
two polysaccharides of a-glucose
AMYLOSE and AMYLOPECTIN
AMYLOSE- gives it that coiled structure
AMYLOPECTIN- gives it the branches
glycogen structure linked to function
structure- made up of ALPHA GLUCOSE molecules joined together to form a HELIX resulting in large but COMPACT molecule that is MORE BRANCHED THAN STARCH
function - it is a store of excess glucose in ANIMALS
structure linking to function-
1. HELIX makes it COMPACT so a lot of glucose can be stored in a small space
2. LARGE SIZE so is INSOLUBLE so does not affect OSMOSIS
3. MANY BRANCHES means GLUCOSE can be RELEASED QUICKLY ( by breaking down the glycogen back into glucose) when required for respiration
what is the main difference between starch and glycogen
STARCH is used as a store of excess glucose in PLANTS
whereas
GLYCOGEN is used as a store of excess glucose in ANIMLAS
hence why their structure different slightly as GLYCOGEN is MORE BRANCHED THAN STARCH as it means glucose can be released quicker which is more beneficial to animals as they are always moving so constantly require glucose for respiration to release ATP whereas plants do not move so require less glucose for respiration
cellulose structure and function
structure- BETA GLUCOSE molecules joined together to form a long UNBRANCHED chain- the CELLULOSE CHAINS are parallel to each other and each chain is linked together by HYDROGEN BONDS to form strong fibres called MICROFIBRILS
function- to provide STRUCTURAL SUPPORT eg CELL WALL IN PLANTS
function linked to function- the HYDORGEN BONDS ensure the MICROFIBRILS are strong and stable giving STRENGTH and RIGIDITY to the plant cell wall, this PREVENTS THE CELL BURSTING when water enters through osmosis so they become turgid
what are most carbohydrates and what are they made out off
most carbohydrates are polymers
the monomers that join together to form the POLYMER carbohydrates are MONOSACCHARIDES
why are the two types of glucose (alpha and beta) described as being isomers
because they have the same molecular formula, but with the atoms connected in different ways.
remember ABBA ( regarding the OH connected to carbon 1)
what is a condensation reaction
when two molecules join together with the formation of a new CHEMICLA BOND and a WATER is released when the bond is formed
when is a glycosidic bond formed
when monosaccharides are joined together through condensation reactions and a molecule of water is released
test for reducing sugar
reducing sugars include all monosaccharides and some disaccharides eg (maltose and lactose)
steps:
add benedict’s reagent (blue) to a sample and heat it in a water bath for 5 mins
if the test is positive it will form a coloured precipitate
colour change can be from BLUE to GREEN, YELLOW, ORANGE OR BRICK-RED depending on the conc of reducing sugar
test for non-reducing sugar
if the test for reducing sugar is negative it could still mean a NON-REDUCING sugar is present
to test for nonreducing suagrs (such as SUCROSE) first you have to BREAK THEM DOWN INTO MONOSACCHARIDES
steps
get a new sample of test solution, add DILUTE HYDROCHLORIC ACID and heat in a water bath that’s been brought to a BOIL.
then you NEUTRALISE it with SODIUM HYDROCARBONATE
then just carry out the benedict’s test as you would for a reducing sugar with the positive result still being the coloured precipitate
if the test is negative the solution will stay blue and that means it doesn’t contain any sugar at all (reducing or non-reducing)
structure of a TRIGLYCERIDE
they are a kind of LIPID
they have ONE MOLECULE OF GLYCEROL with THREE FATTY ACIDS ATTACHED.
structure of a PHOSPHOLIPID
from a TRIGLYCERIDE one fatty acid is removed and a PHOSPHATE group is added
ONE MOLECULE OF GLYCEROL with a PHOSPAHTE GROUP ATTACHED on one side and only TWO fatty acids
how are triglycerides formed
for the 3 fatty acids to attach to the the single glycerol molecule bonds must be formed between them
this takes place through a CONDENSATION REACTION which actually happens THREE TIMES as
there must be three bonds from three sperate parts of the glycerol molecule to the three fatty acids.
so three condensation reactions must occur so THREE WATERS are removed by forming a triglyceride as it involves three separate bonds being made to the same molecule of glycerol
these bonds formed are called ESTER BONDS and there would be THREE in a triglyceride
how are PHOSPHOLIPIDS formed
exact same as the triglyceride but because there are only TWO fatty acids that need to join onto the one GLYCEROL MOLECULE there are only TWO condensation reactions and only TWO ESTER BONDS FORMED.
what are the bonds called that hold together lipids
ESTER bonds
what are the two types of fatty acids
SATURATED and UNSATURATED
the difference is in their hydrocarbon tail (R group)
the SATURATED fatty acids DOES NOT have any double bonds between their carbon atoms (SATURATED with more hydrogen atoms)
the UNSATURATED fatty acid HAS AT LEAST ONE double bond between carbon atoms (which causes the chain to KINK)
features of the fatty acids ‘long hydrocarbon tails’
fatty acids have long hydro-carbon tails as we just saw but the feature of these long hydro carbon chains is that it is hydrophobic (they repel water molecules)
what type of lipid is found in the membrane
the phospholipid
why is the phospholipid used to make up the BILAYER of the cell MEMBRANE
we know the fatty acids tails are HYDROPHOBIC but the PHOSPHATE HEAD on the phospholipid is HYDROPHILIC (attracted to water)
so in the membrane they form a double layer with their heads facing out touching the water (as hydrophilic so like water) on either side and the tails (which are hydrophobic so don’t like water are on the inside away from the water
the two HYDOPHOBIC tails meet in the centre of the bilayer (creating a larger HYDROPHOBIC area) so water-soluble substances can’t easily pass through
the membrane acts as a BARIER to those substances
properties of triglycerides
mainly used as energy store molecules
there long HYDROCARBON TAILS contain lots of CHEMICAL ENERGY so a load of energy is released when they are broken down (lipids contain twice as much energy per gram than carbohydrates)
they are INSOLUBLE so don’t affect the water potential or OSMOSIS
have a relatively low mass therefore a lot can be stored without affecting mass much
the test for lipids
ethanol emulsion test
positive result is a milky emulsion
different bonds in each polymers
sugars (polysaccharides)- GLYCOSIDIC BONDS
lipids (triglyceride/phospholipid)- ESTER BONDS
protiens/ polypeptides- PEPTIDE BONDS
what makes up a protein
AMINO ACIDS are the MONOMERS
DIPEPTIDE is formed when two AMINO ACIDS join together
POLYPEPTIDE is formed when more than two AMINO ACIDS join together
PROTEINS are made out of one or more POLYPEPTIDES
what is the general structure for a protein
amine group(NH2) + Rgroup( central carbon with a hydrogen coming off the bottom and the variable R GROUP coming off the top) + carboxyl group ( which is from chem we know is COOH- c double bond O then OH
how would a DIPEPTIDE and a POLYPEPTIDE be formed
DIPEPTIDE -through a CONDENSATION REACTION between two AMINO ACIDS in which a water molecule is released and PEPTIDE BONDS are formed
POLYPEPTIDE- through a CONDENSTAION REACTION between many AMINO AICDS in which a water molecule is released and PEPTIDE BONDS are formed
what are the four structural levels of proteins
proteins are big complicated molecules, it is much easier if we describe their structure in four ‘levels’
primary
secondary
tertiary
quaternary
PRIMARY STRUCURE of a protein
this the SEQUENCE OF AMINO ACIDS in the POLYPEPTIDE CHAIN
SECONDARY STRUCTURE of a protein
basically the folding or coiling on the primary structure
the POLYPEPTIDE CHAIN (primary structure) doesn’t remain flat and straight, HYDROGEN BONDS form between the AMINO ACIDS in the chain which makes the chain COIL into an ALPHA-HELIX or FOLD into a BETA PLEATED SHEET
the alpha helix or beta pleated sheet is the secondary structure
TERTIARY structure of a protein
the already COILED or FOLDED protein (with a secondary structure) is COILED and FOLDED further to form a UNIQUE 3D SHAPE, MORE BONDS are formed in the tertiary structure to hold it together including HYDROGEN BONDS, IONIC BONDS and DISULPHIDE BONDS.
it is the SEQUENCE of AMINO ACIDS in the POLYPEPTIDE chain (primary structure) that determines the shape of the protein
if the protein is made up off ONLY ONE CHAIN OF POLYPETIDE, the TERTIARY STRUCTURE IS THEIR FINAL 3D STRUCTURE
what determines the tertiary structure of a protein
the primary structure as it is the SEQUENCE OF AMINO ACIDS IN THE POLYPEPTIDE CHAIN which determines the 3D SHAPE OF THE PROTIEN which is what the TERTIARY STUCTURE is.
what structure would a protein made out of one POLYPEPTIDE CHAIN be in
TERTIARY STRUCTURE
what is the QUATERNARY structure
PROTIENS MADE OUT OF MORE THAN ONE CHAIN OF POLYPETIDES
the QUATERNARY STRUCTURE is the way these POLYPEPTIDE CHAINS are ASSEMBLED TOGETHER
proteins in the body
there are loads of proteins in a living organism, they all have different structures and shapes which makes them specialised to carry out particular jobs
enzymes
they are TERTIARY STRUCTURE PROTEINS which LOWER ACTIVATION ENERGY for the reactions they catalyse
usually roughly SPHERICAL due to TIGHT FOLDING
antibodies
involved in IMMUNE RESPONSE
made of two LIGHT POLYPEPTIDE CHAINS and two HEAVY POLYPEPTIDE CHAINS BONDED TOGETHER
TRANSPORT PROTEINS
present in CELL MMBRANE
contain both HYDROPHOBIC and HYDROPHILIC amino acids in their polypeptide chains
this causes the protein to FOLD UP sand from a CHANNEL
these proteins TRANSPORT MOLECULES AND IONS ACROSS MEMBRANE
structural proteins
PHYSICALLY STRONG
consist of LONG POLYPEPTIDE CHAINS lying PARRALEL to each other with CROSS-LINKS between
examples include KERATIN (found in hair and nails) and COLLAGEN (found in connective tissue)
biuret test for proteins
two stages
test solution needs to be alkaline so first you add a few drops of SODIUM HYDROXIDE solution
then you add some copper(11) sulphate solution
protein= purple
no protein= stays blue
what is the general structure of an amino acid
look up
name three bonds which may be formed between polypeptide chains to form a tertiary structure of a protein
Hydrogen bonds, ionic bonds, disulphide bridges
what is a chain of amino acids called
polypeptide chain
